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Date: Sun, 28 Jul 2024 23:22:57 +0200
To: internals@lists.php.net
Subject: [PHP-DEV] Debugging tools
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From: rob@bottled.codes ("Rob Landers")

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Hello internals

I've always found tooling to be one of the biggest accelerators for unde=
rstanding what is going on in a codebase, assuming you know how to use t=
hem. If you've ever tried modifying the language AST and friends, you kn=
ow this can be extremely tricky at times.

For those that want to hack on the languages itself, I've been working o=
n an AST debugging tool running on top of GDB. This allows you to hack o=
n the language, recompile, and see how it affects the PHP compilation. U=
nder the hood, it is really just automated breakpoints and outputting us=
efulish details... it's not too special. Most of the complexity comes in=
 outputting something that makes sense to a human.

Here's a brief animation of it working: https://asciinema.org/a/u9oOUvX5=
eoha93YJWJ5gX2gCb (yes, I'm manually stepping through the code, but this=
 sped up)

There's still a long way to go here, but it really helps to see the yacc=
 rules matching and being applied, or AST being skipped and causing a me=
mory leak. You can even break into a normal gdb session at any point, if=
 needed.

I plan to open this up on GitHub within the next couple of weeks. There =
are some parts that are still a mess that I want to clean up before shar=
ing the code with the world (and a few bugs in the AST view), as well as=
 adding opcodes output.

So, far, I've used it to hunt down my own bugs and grok newer features, =
like property hooks (you can see that one here: https://asciinema.org/a/=
OPZzW2oBr2o8AuOu9YbsBBGap).

Does anything like this exist currently? Would anyone else find this use=
ful?

=E2=80=94 Rob
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<!DOCTYPE html><html><head><title></title><style type=3D"text/css">p.Mso=
Normal,p.MsoNoSpacing{margin:0}
p.MsoNormal,p.MsoNoSpacing{margin:0}</style></head><body><div>Hello inte=
rnals<br></div><div><br></div><div>I've always found tooling to be one o=
f the biggest accelerators for understanding what is going on in a codeb=
ase, assuming you know how to use them. If you've ever tried modifying t=
he language AST and friends, you know this can be extremely tricky at ti=
mes.<br></div><div><br></div><div>For those that want to hack on the lan=
guages itself, I've been working on an AST debugging tool running on top=
 of GDB. This allows you to hack on the language, recompile, and see how=
 it affects the PHP compilation. Under the hood, it is really just autom=
ated breakpoints and outputting usefulish details... it's not too specia=
l. Most of the complexity comes in outputting something that makes sense=
 to a human.<br></div><div><br></div><div>Here's a brief animation of it=
 working:&nbsp;<a href=3D"https://asciinema.org/a/u9oOUvX5eoha93YJWJ5gX2=
gCb">https://asciinema.org/a/u9oOUvX5eoha93YJWJ5gX2gCb</a>&nbsp;(yes, I'=
m manually stepping through the code, but this sped up)<br></div><div><b=
r></div><div>There's still a long way to go here, but it really helps to=
 see the yacc rules matching and being applied, or AST being skipped and=
 causing a memory leak. You can even break into a normal gdb session at =
any point, if needed.<br></div><div><br></div><div>I plan to open this u=
p on GitHub within the next couple of weeks. There are some parts that a=
re still a mess that I want to clean up before sharing the code with the=
 world (and a few bugs in the AST view), as well as adding opcodes outpu=
t.<br></div><div><br></div><div>So, far, I've used it to hunt down my ow=
n bugs and grok newer features, like property hooks (you can see that on=
e here:&nbsp;<a href=3D"https://asciinema.org/a/OPZzW2oBr2o8AuOu9YbsBBGa=
p">https://asciinema.org/a/OPZzW2oBr2o8AuOu9YbsBBGap</a>).<br></div><div=
><br></div><div>Does anything like this exist currently? Would anyone el=
se find this useful?<br></div><div><br></div><div id=3D"sig121229152">=E2=
=80=94 Rob<br></div></body></html>
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